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2014 Election Polling Accuracy

Based on preliminary returns from the 2014 General Election, the Maine People’s Resource Center was once again the most accurate pollster in Maine.

MPRC’s average results for each candidate or referendum position were closest to the actual vote percentages in four of five statewide and congressional races on Election Day. The exception was the U.S. Senate race, where the Portland Press Herald/University of New Hampshire poll had the most accurate results.

Polling nationally was off by about 3.4 percentage points and polls were similarly inaccurate in Maine, particularly in the gubernatorial race. MPRC wasn’t immune to the difficulties presented by this wave election, but the overall average error for its final survey was within the poll’s margin of error.

Among the three polling organizations that surveyed all five statewide and congressional races, MPRC’s final survey had the lowest average error (2.88 percentage points, compared to 3.6 for Pan Atlantic SMS and 4.26 for the Portland Press Herald/University of New Hampshire).

Two other polling organizations each surveyed three of the five statewide and congressional races. The final Bangor Daily News/Ipsos poll had an average of 2.38 percentage points of error for the three races for which it surveyed and the final Critical Insights poll had an average error of 5.56 for the three races for which it reported results.

The measure of error reported (Mosteller 3, with undecided voters assigned proportionally) is generally considered to be the most useful measure in races with significant third-party candidates. Other measures, including a Mosteller 5 analysis of the difference between projected and actual margins of error between the top two candidates in each race, also found MPRC’s results to be the most accurate overall.